The present invention relates generally to a device and non-surgical method for percutaneously shunting certain arterial systems, venous systems and internal organs. More particularly, the present invention relates to a low profile shunting device suitable for non-surgical creation of a communication or xe2x80x9cshuntxe2x80x9d between, for example without limitation, the portal vein and the hepatic vein using catheter techniques introduced through the jugular vein. The device made in accordance with the invention reduces the likelihood of migration of the shunt and is retrievable during the delivery procedure. The device is particularly well suited for delivery through a catheter or the like to a remote location in the patient""s intravenous system or in a vessel or organ within the patient""s body.
A wide variety of shunting devices are used in various medical procedures. Certain intravascular devices, such as catheters and guide wires, may be used to deliver these shunting devices to a specific location within a patient. For example, a catheter may be used to reach a selective coronary artery within the vascular system wherein a shunt is desired. Alternatively, a catheter and/or guidewire may be used to deliver a shunting device to, for example, an interior chamber of the patient""s heart. Certain forms of cogenital disease may require a communication between the right atrium and left atrium. If such a communication is nonexistent or inadequate in size, typically, a communication is created by passing a balloon catheter from the left atrium to the right atrium. This procedure may be referred to as a Rashkind procedure or an atrial septostomy. Over time these communications tend to decrease in diameter. Hence, there is a need for a non-migrating shunt suitable for positioning within a communication formed in the atrial septum. Other uses of a shunt may include delivery of the shunting device to another preselected internal region of the patient. At times it may be desirable to retrieve or reposition the device after it has extended out of a distal end of a delivery catheter. Hence, it would be desirable for the shunting device to be self-expanding yet retrievable.
Shunting devices may be required for treating specific abnormal conditions, such as bi-passing vascular occlusions or some other occlusion within an internal passageway. Without any limitation intended, a patient may require a transjugular intrahepatic portosystemic shunt (TIPS) to provide a communication or shunt between the portal vein and the hepatic vein. In order to interconnect the portal vein and hepatic vein an opening must be created in each vein. The shunt between the portal vein and hepatic vein preferably should expand and have an inner diameter greater than the opening created in the veins. It is desirable for the shunting device to firmly lodge in the veins to avoid rotation and loosening from the veins.
Further, it would be advantageous to provide a shunting device that automatically adjusts to the shape and thickness of the defect. Also, the shunting device should have a means for anchoring each end of the shunt to the corresponding portion of the arterial system, venous system or organ. The inventors of the present invention are not aware of a retrievable, self-expanding shunting device suitable for percutaneous delivery for connecting arterial systems, venous systems, and/or organs. Thus, without limitation, there is a need for a non-invasive, self-expanding, retrievable shunting device. The present invention addresses these and other needs that will become apparent to those skilled in the art from a review of the description of the present invention.
It is accordingly an object of the present invention to provide a reliable, retrievable, low-profile, self-expanding, shunting device, wherein the device is suitable for connecting arterial systems, venous systems, or organs percutaneously. The device of the present invention is preferably formed from a continuous tubular metal fabric and includes two opposing spaced apart xe2x80x9cdiscsxe2x80x9d, patches, or retention skirts interconnected by a central member. Each xe2x80x9cdiscxe2x80x9d includes a bore extending therethrough and the center member includes a central passage interconnecting the bore of each disc, thereby providing a passageway between an outer surface of one disc to an outer surface of the other disc.
When forming these intravascular devices from a resilient metal fabric a plurality of resilient strands or wires are provided, with the metal fabric being formed by braiding the resilient strands to create a resilient material. This braided fabric is then deformed to generally conform to a molding surface of a molding element and the braided fabric is heat treated in contact with the surface of the molding element at an elevated temperature. The time and temperature of the heat treatment is selected to substantially set the braided fabric in its deformed state. After the heat treatment, the fabric is removed from contact with the molding element and will substantially retain its shape in the deformed state. The braided fabric so treated defines a relaxed state of a medical device which can be stretched or expanded and deployed through a catheter into a channel in a patient""s body. Those skilled in the art will appreciate that the cavities of the molds must mirror the desired shape of the device. Additionally, the mold may include cores and/or cams to adequately form the desired shape and passages there through.
Without any limitation intended, one embodiment of the present invention has a specific shape that is particularly well suited for connecting arterial systems, venous systems, or organs. For example, without limitation, one embodiment of the present invention is particularly well suited for creating a transjugular intrahepatic portosystemic shunt. In the preferred embodiment, the device is constructed from a metal fabric having a plurality of woven metal strands. The device has a relaxed low-profile configuration and includes clamps that allow attachment of the device to an end of a delivery device or guide wire (allowing recovery of the device after placement). The device has a proximal end and a distal end, and clamps or means for securing the metal fabric attached to each end. The clamps inhibit unraveling of the metal fabric. The configuration of the preferred embodiment has a relaxed configuration including two enlarged diameter portions and a central portion disposed between the two enlarged diameter portions wherein the central portion includes a passageway extending between an outer surface of each of the two enlarged diameter portions.
In an alternate embodiment of the present invention, a center axis of at least one of the enlarged diameter portions is offset from a center axis of the center portion. Alternatively, the center axis of each of the enlarged diameter portions may be aligned along the same longitudinal axis and/or may be offset from the center axis of the center portion. Further, the separation distance between the two enlarged diameter portions may be less than a separation distance between a portal vein and hepatic vein, for example, thereby ensuring a taught interconnection between the portal vein and the hepatic vein.
Without any limitation intended, the use of the device of the present invention will be described with respects to creating a transjugular intrahepatic portosystemic shunt (TIPS). Those skilled in the art will appreciate that the shunt of the present invention may be useful in several other applications including for example: shunting the aorta and pulmonary artery to increase blood flow which may be required by patient""s having cyanotic cogenital heart disease; cyanotic infants may require a patent ductus arteriosus during development; and/or connection of the gall bladder to the bowel for patient""s with wide spread inoperable cancer on the common bile. Further, the device of the present invention may be positioned within a septal defect to reduce but not eliminate the shunting between the left and right chambers of the heart. Although this identification of suitable uses of the present invention is not exhaustive, those skilled in the art will appreciate that the device of the present invention is not limited to a particularly specialized use.
In use, a guide catheter is positioned and advanced in a patient""s body such that the distal end of the catheter is adjacent a desired treatment site for treating a physiological condition. The medical device of the present invention having a predetermined shape is then stretched and inserted into the lumen of the catheter. The device is urged through the catheter and out the distal end, whereupon, due to its ability to retain the relaxed configuration, it will tend to substantially return to its relaxed state adjacent the treatment site. Once the device is fully deployed, the physician or user may confirm proper deployment through radiographs or other known non-intrusive means of observing the position of the device within the patient. The guide wire or delivery catheter is then released from the clamp and removed.
Hence, the present invention provides a self-expanding, retrievable device suitable for connecting an arterial system a venous system and/or an organ while providing an inward tension between the connecting vessels or tissue. Further, the present invention is particularly well suited for delivery through a catheter or the like to a desired remote location in the patient""s body, wherein the device may be subsequently retrieved. Also, the present invention provides a retrievable, self-expanding shunting device having outer anchoring portions and a central passage. These and other features and advantages of the present invention will become readily apparent to those skilled in the art from a review of the following detailed description of the preferred embodiment in conjunction with the accompanying claims and drawings in which like numerals in the several views refer to corresponding parts.